The invention generally relates to the field of spinal surgery. In particular, the present invention relates to the field of surgical access to the spine. More particularly, the present invention relates to systems and methods of deployment of an implant.
The spine is a series of individual bones called vertebrae, separated by cartilaginous disks. The spine includes seven cervical (neck) vertebrae, 12 thoracic (chest) vertebrae, five lumbar (lower back) vertebrae, and the fused vertebrae in the sacrum and coccyx that help to form the hip region. While the shapes of individual vertebrae differ among these regions, each is essentially a short hollow tube containing the bundle of nerves known as the spinal cord. Individual nerves, such as those carrying messages to the arms or legs, enter and exit the spinal cord through gaps between vertebrae. The spinal disks act as shock absorbers, cushioning the spine, and preventing individual bones from contacting each other. Disks also help to hold the vertebrae together. The weight of the upper body is transferred through the spine to the hips and the legs. The spine is held upright through the work of the back muscles, which are attached to the vertebrae. While the normal spine has no side-to-side curve, it does have a series of front-to-back curves, giving it a gentle “S” shape. The spine curves in at the lumbar region, back out at the thoracic region, and back in at the cervical region.
In some cases, a procedure known as vertebroplasty is used to treat compression fractures in the vertebra such as those caused by osteoporosis, cancer, or stress. Vertebroplasty is an image-guided minimally invasive non-surgical therapy for injecting an orthopedic cement mixture through a needle into the fractured bone. The mixture fills or substantially fills the cavity of the compression fracture and is limited to certain chemical compositions, thereby limiting the amount of otherwise beneficial compounds that can be added to the fracture zone to improve healing. In an alternative procedure known as kyphoplasty, a ballon is first inserted in the compression fracture and the vertebra is expanded before the cement is injected into the newly formed space. All of the above devices do not contain an implant that mechanically deforms in bone creating superior interdigitation and restore vertebral body height. However, these devices are readily available in prepackaged and sterilized form along with disposable instrumentation.
Examples of alternatives to the above devices may be found in U.S. Pat. Pub. No. 2008/0071356, entitled “Expandable Support Device and Method of Use” and incorporated herein by reference. However, the instrumentation and tools for these types of devices requires considerable amounts of force to deploy the devices. Cleaning and sterilization of the reusable instrumentation requires additional effort and time and may be costly over long periods of time. The instruments and methods of the present disclosure attempts to solve these problems as well as others.